130 lines
3.9 KiB
TypeScript
130 lines
3.9 KiB
TypeScript
type ScrollBehavior = 'auto' | 'smooth' | 'instant';
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export function getScrollContainer(el: HTMLElement | null): HTMLElement | null {
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if (el == null || el.tagName === 'HTML') return null;
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const overflow = window.getComputedStyle(el).getPropertyValue('overflow-y');
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if (overflow === 'scroll' || overflow === 'auto') {
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return el;
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} else {
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return getScrollContainer(el.parentElement);
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}
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}
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export function getStickyTop(el: HTMLElement, container: HTMLElement | null = null, top = 0) {
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if (!el.parentElement) return top;
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const data = el.dataset.stickyContainerHeaderHeight;
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const newTop = data ? Number(data) + top : top;
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if (el === container) return newTop;
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return getStickyTop(el.parentElement, container, newTop);
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}
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export function getScrollPosition(el: HTMLElement | null): number {
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const container = getScrollContainer(el);
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return container == null ? window.scrollY : container.scrollTop;
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}
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export function onScrollTop(el: HTMLElement, cb: () => unknown, tolerance = 1, once = false) {
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// とりあえず評価してみる
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if (isTopVisible(el)) {
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cb();
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if (once) return null;
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}
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const container = getScrollContainer(el) ?? window;
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const onScroll = ev => {
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if (!document.body.contains(el)) return;
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if (isTopVisible(el, tolerance)) {
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cb();
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if (once) removeListener();
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}
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};
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function removeListener() { container.removeEventListener('scroll', onScroll); }
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container.addEventListener('scroll', onScroll, { passive: true });
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return removeListener;
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}
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export function onScrollBottom(el: HTMLElement, cb: () => unknown, tolerance = 1, once = false) {
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const container = getScrollContainer(el);
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// とりあえず評価してみる
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if (isBottomVisible(el, tolerance, container)) {
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cb();
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if (once) return null;
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}
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const containerOrWindow = container ?? window;
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const onScroll = ev => {
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if (!document.body.contains(el)) return;
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if (isBottomVisible(el, 1, container)) {
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cb();
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if (once) removeListener();
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}
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};
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function removeListener() {
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containerOrWindow.removeEventListener('scroll', onScroll);
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}
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containerOrWindow.addEventListener('scroll', onScroll, { passive: true });
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return removeListener;
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}
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export function scroll(el: HTMLElement, options: ScrollToOptions | undefined) {
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const container = getScrollContainer(el);
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if (container == null) {
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window.scroll(options);
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} else {
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container.scroll(options);
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}
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}
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/**
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* Scroll to Top
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* @param el Scroll container element
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* @param options Scroll options
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*/
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export function scrollToTop(el: HTMLElement, options: { behavior?: ScrollBehavior; } = {}) {
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scroll(el, { top: 0, ...options });
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}
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/**
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* Scroll to Bottom
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* @param el Content element
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* @param options Scroll options
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* @param container Scroll container element
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*/
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export function scrollToBottom(
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el: HTMLElement,
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options: ScrollToOptions = {},
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container = getScrollContainer(el),
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) {
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if (container) {
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container.scroll({ top: el.scrollHeight - container.clientHeight + getStickyTop(el, container) || 0, ...options });
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} else {
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window.scroll({
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top: (el.scrollHeight - window.innerHeight + getStickyTop(el, container) + (window.innerWidth <= 500 ? 96 : 0)) || 0,
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...options,
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});
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}
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}
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export function isTopVisible(el: HTMLElement, tolerance = 1): boolean {
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const scrollTop = getScrollPosition(el);
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return scrollTop <= tolerance;
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}
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export function isBottomVisible(el: HTMLElement, tolerance = 1, container = getScrollContainer(el)) {
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if (container) return el.scrollHeight <= container.clientHeight + Math.abs(container.scrollTop) + tolerance;
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return el.scrollHeight <= window.innerHeight + window.scrollY + tolerance;
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}
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// https://ja.javascript.info/size-and-scroll-window#ref-932
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export function getBodyScrollHeight() {
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return Math.max(
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document.body.scrollHeight, document.documentElement.scrollHeight,
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document.body.offsetHeight, document.documentElement.offsetHeight,
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document.body.clientHeight, document.documentElement.clientHeight,
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);
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}
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